Many direct view flat panel displays generate images by selectively modulating a light intensity emitted by each pixel in an array across the panel. In full color displays, each pixel is composed of differently colored subpixels (e.g., red, green, blue or cyan, yellow, magenta), the display emitting varying amounts of colored light from each subpixel that additively combine so that each pixel, as a whole, appears a desired color that is a combination of the subpixel light.
Some displays use light emitting diodes (LEDs), including inorganic or organic LEDs, to generate an image. For instance, each subpixel can include a red, green, or blue LED to provide full color images. Typically, each LED emits light substantially isotropically into a hemisphere so that multiple viewers can view the same displayed image from various locations about the display. For example, the LEDs can be Lambertian emitters, where the relative intensity of light falls off as the square of the cosine of the viewing angle as one moves off the axis normal to the display. Indeed, a wide viewing angle (e.g., as much as 170° in the horizontal viewing plane) is a desirable feature in many applications, such as displays used as large, wall-mounted televisions.